begin in earnest until 13 months after the contract was awarded. Unexpected geological conditions at the dam site led to landslides and slower tunnel excavation. By November 2007, the river was successfully diverted and in April of the next year, the foundation was clear for construction. Before the foundation was fully prepared it was discovered that bedrock was reached sooner than expected. This led to an alteration in the dam's design for stability. While the dam was being re-designed, concrete was placed over the foundation to protect it from the upcoming monsoon floods as the cofferdams stood a good chance of not protecting the foundation from the strong floods. The re-design was completed in October 2008 and soon after the foundation was once again cleared. In May 2009, work was suspended because of the monsoon season and re-commenced in November of that year. As of November 2011, the dam reached an elevation of , just below the spillway elevation of . On 16 December 2011, construction equipment was halted by protests. The construction cost has gone up by about 1,200 crore owing to forced suspension of work since December 2011. NHPC has already spent about 6,600 crore, according to a status report prepared by the company. Officially expected to be competed in January 2023, the hydroelectric generators will begin generating 500 MW of electricity, gradually increasing to 2000 MW. Environmental impact Some environmental impacts unique to very large dams will result from completion of the Subansiri Project, both upstream and downstream of the dam site. These impacts will include ecosystem damage and loss of land. The reservoir of the Subansiri Project will submerge a length of the Subansiri river and occupy which includes Himalayan subtropical pine forests, Himalayan subtropical broadleaf forests, part of the Tale Valley Wildlife Sanctuary, an elephant corridor and some subsistence agriculture fields. Thirty eight families will be displaced if the dam is completed, according to official data. Downstream Water flow downstream will be regulated by the dam which is expected to result in low releases (6 m3/s) during winter and very high releases (2,560 m3/s) when energy is being generated. The project has met stiff resistance from several groups including All Assam Students’ Union and the Krishak Mukti Sangram Samiti, who are apprehensive about safety and the project’s downstream impact. References Dams in Arunachal Pradesh Dams in Assam Dams under construction Dams in the Brahmaputra River